How to choose a suitable directional drilling rig guidance system?

1. Laboratory test
Sensor calibration test: In a laboratory environment, use professional calibration equipment to perform separate calibration tests on various sensors in the guidance system, such as inclination sensors, azimuth sensors, position sensors, etc. By comparing with known standard values, check whether the measurement error of the sensor is within the allowable range. For example, for the inclination sensor, it can be placed on a precision tilting table, set different inclination angles, and observe the deviation between the measured value of the sensor and the actual inclination angle. Generally, the measurement accuracy of the inclination sensor is required to be within ±0.1°.
Signal transmission test: Simulate the signal transmission conditions in the actual drilling process to test the signal transmission performance of the guidance system. Build a signal transmission test platform, set different transmission distances, interference environments and other factors, and detect the signal strength, stability and bit error rate. For example, in the presence of strong electromagnetic field interference, observe the packet loss rate of wireless signal transmission. If the packet loss rate exceeds a certain threshold, it means that the signal transmission performance is poor, which may affect the normal operation of the guidance system.
2. On-site test
Static accuracy test: At the construction site, place the drill bit of the directional drill on a fixed point with a known position and posture, start the guidance system, record the measured position, inclination, azimuth and other parameters, and compare them with the actual known values. Take the average value of multiple measurements and calculate the measurement error. For example, on the horizontal ground, set the position coordinates and levelness of the drill bit to known standard values, measure and compare their deviations through the guidance system. If the horizontal position deviation exceeds ±0.2 meters, the vertical position deviation exceeds ±0.1 meters, or the inclination and azimuth deviations exceed the specified accuracy range, it means that the static accuracy of the guidance system does not meet the requirements.
Dynamic accuracy test: Perform dynamic accuracy test during the actual drilling process, which is the test method that best reflects the performance of the guidance system. Select a representative drilling path, pre-set the drilling trajectory, and during the drilling process, record the trajectory data measured by the guidance system in real time, and compare and analyze it with the preset trajectory. Calculate the horizontal deviation, vertical deviation, average deviation and other indicators of the trajectory to evaluate the accuracy of the guidance system under dynamic conditions. For example, in a drilling test with a length of 50 meters, if the average value of the horizontal deviation exceeds ±0.3 meters and the average value of the vertical deviation exceeds ±0.2 meters, it indicates that the dynamic accuracy of the guidance system needs to be improved.
Repeatability test: Under the same conditions, perform the same drilling operation multiple times, record the measurement data and drilling trajectory of the guidance system each time, and observe the repeatability of the measurement results and trajectory. Evaluate the stability and repeatability of the guidance system by calculating the deviation range between multiple test results. If the deviation range of each test is small, it means that the guidance system has good repeatability and stability; otherwise, there may be problems with system instability or inaccurate measurement.
3. Comparison test
Comparison with known high-precision systems: Install the guidance system to be tested and the known high-precision guidance system on the same directional drilling rig at the same time, perform the same drilling operation, and compare the trajectory data and accuracy indicators measured by the two. If the deviation between the measurement results of the system to be tested and the high-precision system is within a reasonable range, it means that its performance and accuracy basically meet the requirements; if the deviation is large, it is necessary to further analyze the cause and make improvements.
Comparative tests under different working conditions: Tests are conducted for different formation conditions, drilling depths, drilling diameters and other working conditions, and the performance and accuracy of the guidance system under different working conditions are compared. For example, drilling tests are conducted in sandy and rocky formations to observe the measurement accuracy and trajectory control capabilities of the guidance system under different formation resistances and geological structures, so as to comprehensively evaluate its adaptability and reliability.
4. Data analysis and evaluation
Error analysis: Detailed error analysis of various data collected during the test, including systematic errors, random errors, etc. Parameters such as the mean and standard deviation of the errors are calculated by statistical methods to determine the distribution law and main sources of the errors. For example, if a large systematic error is found in the azimuth measurement, it may be due to inaccurate calibration of the geomagnetic sensor or interference from the surrounding magnetic field, and targeted adjustments and improvements are required.
Performance evaluation indicators: Establish a set of scientific and reasonable performance evaluation indicator systems, comprehensively consider factors such as accuracy, stability, real-time, and reliability, and comprehensively evaluate the overall performance of the guidance system. For example, a weighted average method can be used to assign corresponding weights according to the importance of different indicators, and a comprehensive performance score can be calculated to serve as a basis for judging whether the guidance system meets the engineering requirements.